The 'E' variant is a white/ss case based on the $79.95 price in this 1965 ad and the 1964 pricelist shows no other Date King model at the $79.95 price - only the 'E'; that variant also uses the linen dial, which this watch does not appear to have. I would vote unknown-variant Date King based on that info and the discussion with this matching 1965 watch in the database.